An electronic component mounting line for producing a mounting circuit board in which electronic components are mounted on a circuit board is configured by connecting a screen printing apparatus for printing a paste for bonding an electronic component such as a semiconductor device on the circuit board, to the upstream side of an electronic component mounting apparatus which mounts the electronic component onto the circuit board. As a type of a circuit board on which electronic components are to be mounted, conventionally, a so-called cavity circuit board is known in which an electrode pattern is formed on both the upper surface of the circuit board, and the bottom surfaces of recesses opening in the upper surface of the circuit board, and such a circuit board is used in various apparatuses as a lightweight and high-density circuit board (Patent Reference 1). In screen printing which prints a paste for bonding an electronic component on such a cavity circuit board, a three-dimensional screen mask is used which has a planar portion that is to be contacted with the upper surface of a circuit board, and fitting portions that are downward projected from the planar portion to be fitted to recesses. When such a three-dimensional screen mask is used, a paste can be printed simultaneously on the upper surface of the circuit board, and the bottom surfaces of the recesses.